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The present invention relates to aerosol dispensing devices, and in particular to valve assemblies that provide automatic dispensing of aerosol content at predetermined time intervals, without requiring the use of electrical power.
Aerosol cans dispense a variety of ingredients. Typically, an active is mixed with a propellant which may be gaseous, liquid or a mixture of both (e.g. a propane/butane mix; carbon dioxide), and the mixture is stored under pressure in the aerosol can. The active mixture is then sprayed by pushing down/sideways on an activator button at the top of the can that controls a release valve. For purposes of this application, the term xe2x80x9cchemicalxe2x80x9d is used to mean liquid, liquid/gas, and/or gas content of the container (regardless of whether in emulsion state, single phase, or multiple phase).
The pressure on the button is typically supplied by finger pressure. However, for fragrances, deodorizers, insecticides, and certain other actives which are sprayed directly into the air, it is sometimes desirable to periodically refresh the concentration of active in the air. While this can be done manually, there are situations where this is inconvenient. For example, when an insect repellant is being sprayed to protect a room overnight (instead of using a burnable mosquito coil), the consumer will not want to wake up in the middle of the night just to manually spray more repellant.
There are a number of prior art systems for automatically distributing actives into the air at intermittent times. Most of these rely in some way on electrical power to activate or control the dispensing. Where electric power is required, the cost of the dispenser can be unnecessarily increased. Moreover, for some applications power requirements are so high that battery power is impractical. Where that is the case, the device can only be used where linkage to conventional power sources is possible.
Other systems discharge active intermittently and automatically from an aerosol can, without using electrical power. For example, U.S. Pat. No. 4,077,542 relies on a biased diaphragm to control bursts of aerosol gas at periodic intervals. See also U.S. Pat. Nos. 3,477,613 and 3,658,209. However, biased diaphragm systems have suffered from reliability problems (e.g. clogging, leakage, uneven delivery). Moreover, they sometimes do not securely attach to the aerosol can.
Moreover, the cost of some prior intermittent spray control systems makes it impractical to provide them as single use/throw away products. For some applications, consumers may prefer a completely disposable product.
Thus, a need still exists for improved, inexpensive automated aerosol dispensers that do not require electrical power.
In one aspect the invention provides a valve assembly that is suitable to dispense a chemical from an aerosol container. It can automatically iterate between an accumulation phase where the chemical is received from the container, and a spray phase where the received chemical is automatically dispensed at intervals.
There is a housing mountable on an aerosol container, a movable diaphragm associated with the housing which is linked to a sloped track, the diaphragm being biased towards a first configuration, and an accumulation chamber inside the housing for providing variable pressure against the diaphragm. There is also a first passageway in the housing suitable for linking an interior portion of the aerosol container with the accumulation chamber.
A second passageway in the housing is suitable for linking the accumulation chamber with an outlet of the valve assembly, and a valve stem is positioned in the housing which the sloped track can ride along. A pawl is rotatably positioned on the sloped track to ride on the sloped track. When the diaphragm is in the first configuration the valve assembly can prevent spray of the chemical out of the valve assembly and permit chemical to flow from the aerosol container into the accumulation chamber via the first passageway. When the pressure of chemical inside the accumulation chamber exceeds a specified threshold the diaphragm can move from the first configuration to a second configuration wherein spray is permitted to exit the valve assembly.
In preferred forms a portion of the diaphragm blocks off the first passageway when the diaphragm is in the second configuration, a portion of the sloped track restricts flow to the second passageway when the diaphragm is in the first configuration. A pawl can be linked to a rotor, the rotor having an upper surface that can be at least partially coated with putty. The sloped track preferably is helically sloped. The pawl rides on it to resist movement of the diaphragm from the first configuration to the second configuration. Pressure supplied by the diaphragm towards the pawl can cause the pawl to rotate, thereby permitting movement of the diaphragm towards the second configuration.
A toe of the pawl will flare radially outwardly off of the track when the diaphragm approaches the second configuration. Also, the diaphragm has a radially outward section, a radially inward section, and an orifice there between. In another aspect, the accumulation chamber has a base that is sloped so as to direct liquid chemical that may collect in the accumulation chamber towards the first passageway.
If desired, a spring can be disposed in the housing to resist axial movement of the diaphragm from the first to the second configuration. Also, a porous barrier can be disposed within the housing between the aerosol container and the first passageway. These changes will slow the interval between bursts.
In another aspect, methods are provided for using these valve assemblies with aerosol containers are also disclosed.
The present invention achieves a secure mounting of a valve assembly on an aerosol can, yet provides an actuator that has two modes. In one mode the valve assembly is operationally disconnected from the actuator valve of the aerosol container (a mode suitable for shipment or long-term storage). Another mode operationally links the valve assembly to the aerosol container interior, and begins the cycle of periodic and automatic dispensing of chemical there from. Importantly, periodic operation is achieved without requiring the use of electrical power to motivate or control the valve.
The valve assembly has few parts, and is inexpensive to manufacture and assemble. Further, it does not require the use of small orifices which might be susceptible to clogging, and it is otherwise relatively self-cleaning to help avoid clogs and/or inconsistent bursts. For example, the movement of the pawl along the sloped track avoids residue accumulation along the track.